The present invention relates to an accelerator system for accelerating an ion beam to thereby make available the beam for therapy. More particularly, the present invention is concerned with an improvement of the accelerator system such that the accelerated ion beam can be utilized for therapy with a high efficiency.
As one of the accelerator systems designed for generating an ion beam (hereinafter also referred to simply as the beam) for utilization thereof for therapy, such an accelerator system is heretofore known which is destined for use in practicing treatment of cancer by irradiating an affected part of a cancer suffering patient. A typical one of such accelerator systems is disclosed in Japanese Patent Application Laid-Open Publication No. 303710/1995 (JP-A-7-303710). More specifically, described in this publication is an accelerator system in which an ion source and a pre-accelerator(s) are put into operation in response to a trigger signal generated in dependence on movement (or positional change) of an affected part of a patient to thereby accelerate the beam for injecting it into a synchrotron in which the beam is further accelerated, whereon the affected part of the patient is irradiated with the accelerated beam outputted from the synchrotron.
Further, another type of accelerator system for generating an accelerating beam for making use of it for therapy is disclosed in xe2x80x9cPROC. OF THE SECOND INTxe2x80x21 SYMP. ON PET IN ONCOLOGYxe2x80x9d, May 16-18, 1993, Sendai Japan. Described in this publication is an accelerator system for producing an radioisotope by irradiating a target such as a nitrogen gas or the like for the purpose of utilizing it in diagnoses.
The accelerator system for the treatment of cancer and the accelerator system for producing the radioisotope mentioned above are employed for the purpose of medical treatments, and thus it is considered that both the systems may be installed in one and the same facility. In this conjunction, each of these accelerator systems is of a very large size and bulky. Consequently, installation of both the systems in one and the same facility at a same site requires a considerably large space. Consequently, there exists a demand for miniaturization of these accelerator systems. Besides, reduction of the manufacturing costs of these systems is also a matter of concern, needless to say.
Further, it is noted that in the accelerator system destined for the treatment of cancer, the beam generated by the ion source is made use of only for a short period during which the beam is injected into the synchrotron. To say in another way, during a period in which the beam is accelerated in the synchrotron and ejected therefrom, the beam being generated in the ion source is not utilized. Thus, it can be said that the accelerator system for the treatment of cancer is very poor in respect to the utilization efficiency of the ion beam.
Naturally, operations of the ion source and the pre-accelerator can be stopped during the period in which the beam acceleration and ejection or extraction is carried out in the synchrotron. In that case, however, the availability factor of the ion source and the pre-accelerator will be lowered, to a disadvantage.
In the light of the state of the art described above, it is an object of the present invention to provide an accelerator system which can be realized in a small size at low manufacturing cost and which can nonetheless ensure a high utilization efficiency of the ion beam.
In view of the above and other objects which will become apparent as the description proceeds, there is provided according to an aspect of the present invention an accelerator system which includes an ion source for generating an ion beam, a pre-accelerator for accelerating the ion beam generated by the ion source, a radioisotope producing unit for irradiating a target with the ion beam accelerated by the pre-accelerator for thereby producing a radioisotope, a synchrotron into which the ion beam accelerated by the pre-accelerator is injected and from which the ion beam is ejected after the acceleration, and a selector electromagnet for introducing the ion beam accelerated by the pre-accelerator into either the radioisotope producing unit or the synchrotron.
By virtue of the incorporation of the selector electromagnet in the accelerator system for introducing the ion beam accelerated by the pre-accelerator into either the radioisotope producing unit or the synchrotron, as described above, the ion beam generated in the ion source can be constantly and consecutively utilized by the radioisotope producing unit and the synchrotron owing to such arrangement that the ion beam is injected into the synchrotron when it is demanded while otherwise the ion beam is supplied to the radioisotope producing unit, whereby the beam utilization efficiency can be improved and enhanced significantly. In particular, owing to the arrangement that the ion source and the pre-accelerator are shared in use by the synchrotron which demands the ion beam only intermittently and the radioisotope producing unit which requires the beam continuously, the utilization efficiency of the beam can be enhanced remarkably.
Furthermore, because the ion source and the pre-accelerator are made use of as shared between the radioisotope producing unit and the synchrotron, the system as a whole can be implemented in a small size at low manufacturing cost when compared with the arrangement in which the ion source and the pre-accelerator(s) are provided separately for the radioisotope producing unit and the synchrotron, respectively.
The above and other objects, features and attendant advantages of the present invention will more easily be understood by reading the following description of the preferred embodiments thereof taken, only by way of example, in conjunction with the accompanying drawings.